A vulnerability exists in the Cisco IOS Software that may allow a remote application or device to exceed its authorization level when authentication, authorization, and accounting (AAA) authorization is used. This vulnerability requires that the HTTP or HTTPS server is enabled on the Cisco IOS device.

Products that are not running Cisco IOS Software are not vulnerable.

Cisco has released free software updates that address these vulnerabilities.

The HTTP server may be disabled as a workaround for the vulnerability described in this advisory.

Note: The March 28, 2012, Cisco IOS Software Security Advisory bundled publication includes nine Cisco Security Advisories. Each advisory lists the Cisco IOS Software releases that correct the vulnerability or vulnerabilities detailed in the advisory as well as the Cisco IOS Software releases that correct all vulnerabilities in the March 2012 bundled publication.

Any device running Cisco IOS Software release after 12.2 that has an HTTP or HTTPS server configured is affected by this vulnerability if AAA authorization is used.
To determine if an HTTP or HTTP server is configured with an HTTP or HTTPS server, issue the show ip http server status | include status command. The following example illustrates a Cisco IOS device with an HTTPS server enabled and the HTTP server disabled.

To determine if AAA authorization is used, an administrator can log in to the device and issue the show run | include aaa authorization command in privileged EXEC mode. If there is an entry that shows aaa authorization commands, as shown in the following example, then AAA authorization is configured.

To determine the Cisco IOS Software release that is running on a Cisco product, administrators can log in to the device and issue the show version command to display the system banner. The system banner confirms that the device is running Cisco IOS Software by displaying text similar to "Cisco Internetwork Operating System Software" or "Cisco IOS Software." The image name displays in parentheses, followed by "Version" and the Cisco IOS Software release name. Other Cisco devices do not have the show version command or may provide different output.

The following example identifies a Cisco product that is running Cisco IOS Software Release 15.0(1)M1 with an installed image name of C3900-UNIVERSALK9-M:

If you are not running Cisco IOS or IOS XE Software, you are not affected by this vulnerability. Devices that are not using AAA authorization or that do not have an HTTP or HTTPS server configured are not affected by this vulnerability.

Cisco IOS XR is not affected by this vulnerability.

No other Cisco products are currently known to be affected by this vulnerability.

A vulnerability exists that may allow the Cisco IOS command authorization to be bypassed, allowing a remote, authenticated HTTP or HTTPS session to execute any Cisco IOS command that is configured for their authorization level. This vulnerability does not allow unauthenticated access; a valid username and password are required to successfully exploit this vulnerability. Additionally, the vulnerability does not allow a user to execute commands that are not configured for their privilege level.

Successful exploitation of the vulnerability may allow the Cisco IOS command authorization to be bypassed, allowing a remote, authenticated HTTP or HTTPS session to execute any Cisco IOS command that is configured for its authorization level.

When considering software upgrades, customers are advised to consult the Cisco Security Advisories and Responses archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

Cisco IOS Software

Each row of the following Cisco IOS Software table corresponds to a Cisco IOS Software train. If a particular train is vulnerable, the earliest releases that contain the fix are listed in the First Fixed Release column. The First Fixed Release for All Advisories in the March 2012 Bundled Publication column lists the earliest possible releases that correct all the published vulnerabilities in the Cisco IOS Software Security Advisory bundled publication. Cisco recommends upgrading to the latest available release, where possible.

* Cisco Catalyst 3550 Series Switches support the Internet Key Exchange (IKE) feature and are vulnerable to Cisco bug ID CSCts38429 when the devices are running Layer 3 images; however, this product reached the End of Software Maintenance milestone. Cisco 3550 Series SMI Switches that are running Layer 2 images do not support IKE and are not vulnerable. No other Cisco devices that run 12.2SE-based software are vulnerable.

If the HTTP and HTTPS servers are not required, they may be disabled with the commands no ip http server and no ip http secure-server.

However, if web services are required, a feature was introduced in 12.3(14)T and later in which selective HTTP and HTTPS services could be enabled or disabled. The WEB_EXEC service provides a facility to configure the device and retrieve the current state of the device from remote clients.

It is possible to disable the WEB_EXEC service while still leaving other HTTP services active. If an installation does not require the use of the WEB_EXEC service, then it may be disabled using the following procedure:

If the HTTP server and WEB_EXEC service are required, it is a recommended best practice to limit which hosts may access the HTTP server to allow only trusted sources. An access list can be applied to the HTTP server to limit which hosts are permitted access. To apply an access list to the HTTP server, use the following command in global configuration mode: ip http access-class {access-list-number | access-list-name}.

The following example shows an access list that allows only trusted hosts to access the Cisco IOS HTTP server:

Cisco has released free software updates that addresses the vulnerability described in this advisory. Prior to deploying software, customers are advised to consult their maintenance providers or check the software for feature set compatibility and known issues that are specific to their environments.

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, upgrades should be obtained through the Software Center on Cisco.com at http://www.cisco.com.

Customers with Cisco products that are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers, should contact that organization for assistance with the appropriate course of action.

The effectiveness of any workaround or fix depends on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Because of the variety of affected products and releases, customers should consult their service providers or support organizations to ensure that any applied workaround or fix is the most appropriate in the intended network before it is deployed

Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco Technical Assistance Center (TAC):

+1 800 553 2447 (toll free from within North America)

+1 408 526 7209 (toll call from anywhere in the world)

e-mail: tac@cisco.com

Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Customers without service contracts should request free upgrades through the TAC.

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